Aims and Rationale: The primary objective of this research is to produce an empirically validated treatment that increases smoking cessation in Veterans with posttraumatic stress disorder (PTSD), one that can be easily integrated into smoking cessation clinics and/or mental health clinics within Veterans Administration (VA) facilities. PTSD is highly prevalent in the VA patient population and is associated with a rate of smoking (53% - 66%) that far exceeds that of VA enrollees in general (22%). PTSD is also associated with unusually high rates of smoking cessation treatment failure. The disparity in smoking cessation outcomes amongst veterans with PTSD may occur because standard smoking cessation treatment does not address PTSD-specific vulnerabilities. Veterans with smoking-PTSD comorbidity may respond optimally to treatment that addresses PTSD and associated affective symptoms, because such symptoms can both reinforce smoking and undermine quit attempts. Recent evidence shows that behavioral activation therapy (BA), a behavioral treatment that increases engagement in reinforcing activities, significantly reduces PTSD symptoms. BA may improve smoking cessation outcomes amongst veterans with PTSD because it reduces overall PTSD symptom severity and affective distress (low positive affect, high negative affect), which can cause smoking relapse. The proposed research will determine whether BA as an adjunct to standard smoking cessation treatment (ST+BA) is superior to a comparably intense combination of standard smoking cessation treatment + health and smoking education (ST+HSE) in improving smoking cessation outcomes among veterans with PTSD. The HSE intervention is intended to constitute a credible intervention that controls for contact time. Secondary objectives are to determine if BA improves PTSD symptomatology and associated affective distress, and to identify potential mediators of BA on smoking outcomes. Methods: A total of 120 veterans with PTSD who are motivated to quit smoking will attend an initial diagnostic and baseline assessment session. Those who are interested, eligible, and who provide consent will be randomly assigned to receive ST+BA or ST+HSE and will be contacted by their individual study therapist to schedule the first treatment session. Participants will be stratified into treatment groups based on: 1) major depressive disorder (MDD; present versus absent), and 2) PTSD symptom severity. All participants will receive eight, individual sessions of ST+BA or ST+HSE. All participants will receive 20 minutes of identical standard smoking cessation treatment in each of the eight sessions. Those in the ST+BA condition will receive an additional 30 minutes of behavioral activation therapy; those in the ST+HSE condition will receive an additional 30 minutes of health education and information about smoking. All participants will receive 8 weeks of the nicotine patch. Smoking cessation outcomes will be assessed 2, 4, 8, 16, and 26 weeks after the quit date. Significance: This research has important clinical and public health significance because smoking is especially common among veterans with PTSD and it is the leading preventable cause of disease and disability. Reducing smoking rates among veterans with PTSD would result in substantially lower smoking-related illness and death in this vulnerable group of smokers. It would also reduce tobacco related healthcare costs charged to the VA. Study methods and findings may potentially be extended to smoking cessation treatment for patients with mental health disorders other than PTSD.